So if you do it right, (read all four pages of the forum thread - there's good reliable information there), an acetone dip will not prevent a coin from being graded, though other unrelated factors may.

How long should coins be immersed in acetone? Do you mind sharing a quick step by step process? Thanks for the valuable info.

Acetone, and similar chemicals like methyl ethyl ketone (MEK), are just solvents. A solvents is basically something that dissolves and rinses stuff. If your coin has some type of plastic goo on it, a solvent like acetone will soften it up and dissolve it away. Acetone also has low viscosity, which means it flows quickly. That makes it good for washing off other debris like dust and lint. Oily fingerprints will dissolve away too. Acetone has a high vapor pressure, which means it will evaporate quickly. As long as your acetone is clean, it will leave no trace that it was ever there.

Soaking coins in acetone will give additional time for the acetone to dissolve solidified oils and residues. Anything I can think of would be totally dissolved within an hour or so, depending on whether there's solid dirty stuff embedded in it that doesn't dissolve.

If you soak your coins, be sure to open a window or something to prevent the buildup of acetone vapors, which are poisonous, flammable, and potentially explosive. Merely turning on a light switch is enough to make it go boom if there is a lot of vapor in the air. Acetone is miraculous in how quickly and safely it can clean your coins, but also in how quickly it can cause a catastrophe. It is more dangerous than gasoline and alcohol, but not quite as dangerous as propane or butane. I would place it somewhere on the danger scale just below napalm.

Paint thinner is usually made of something like (or exactly like) acetone or MEK. For safety, you can use the same precautions as you would with paint thinner.